The migration from our historical to our new infrastructure provider allowed us to double the RAM size of the servers hosting our MySQL database. During this intervention, every custom MySQL server configuration parameters have been ported from the old MySQL server to the new one.

Nevertheless, the RAM size increase of the servers was not properly taken into account in the new configuration, as the buffer size kept using a value fit for our old RAM size, but too small for our new RAM power. As a consequence, MySQL was sometimes retrieving data from disk, instead of from memory, which degraded performance significantly and created slowdowns on the platform.

Everything went back to normal after doubling the MySQL buffer size, reflecting our new RAM size.